QM - MATERIAL GROUPS

Dear friends

How to create material groups for ROH, Semifinished, Phantom & finished goods materials so that the same can be used in the Material Master - MM01. Shall we have to create the material groups in the SPRO Customising screen and how is it done in the customising.Is the grouping useful only to seggregate different types of materials or is there any specific use. Also what is the use of CLASSIFICATION header in the Material Master.

regards

Selva